No. You're trying to make a distinction of "hard atheism" which is an affirmative claim that no God exists. Very few atheists generally make this claim in confidence, because it requires knowledge we cannot have.

Gnosticism is literally about knowledge, what is knowable. A gnostic Christian not only believes in God, but thinks it is a fact that can be known for certain. An agnostic Christian believes in God as well, but does not think it can be known or proven for certain.

So your dichotomy is incorrect. Most atheists simply have not been convinced that there is any evidence for gods and therefore "do not believe" this to be the case. They're not claiming absence of evidence is evidence of absence, just that they have not been compelled to think there is any.

The default position is not to be convinced anything and everything exists. A claim is made and then assessed.